For many years, platen presses operated by manually actuated screw jacks and more recently by hydraulic cylinder devices, have been employed to extract juice from fruit, such as apples. These presses conventionally include horizontally disposed upper and lower platens, which are permanently supported in the press for vertically directed relative movements and, if desired, one or more additional platen-like elements, which may be removably positioned in the press in order to permit a plurality of layers of fruit to be pressed at the same time. The fruit to be pressed is preferably cut in small pieces and arranged to assume a relatively thin layer between each pair of adjacent platens; a sheet of filter cloth, such as "cheesecloth", being folded to define a "bag" enclosing the fruit in each layer. Characteristic of this type of press is the slow application of pressure to thin layers of fruit, which allows for maximum percentage extraction of juices, while permitting pieces of fruit to serve as filtering medium resulting in the production of high quality juice, i.e., a minimum pulp content, which may be marketed without the need for performing subsequent filtering or clarification operations. However, conventional platen press units are labor intensive and have a low output capacity, due to the time involved in charging the press with fruit and removing therefrom the layer(s) of compressed pulp or "cake" remaining after the juice has been extracted.
Commercial juice extraction operations have placed in use various types of automatic, large capacity presses, but with varying degrees of success. In this respect, it has been found that those types of automatic press units, which are most efficient from the standpoint of achieving maximum juice extraction tend to suffer from the drawback that the juice is normally of lower quality, i.e., has an unacceptably large pulp content, and this necessitates the utilization of expensive juice filtration or clarifying equipment/procedures. Other types of commercially available automatic press units are capable of producing high quality juice, but appear to universally suffer from the drawback that only a portion of available juice is actually extracted from the pulp. Thus, economic considerations require that the pulp from this latter type of press unit be subjected to a "second-time" press operation in basic platen press units of the type described above.
Further, it has been recognized that the drawbacks of both basic platen press units and automatic large capacity press units would be avoided, if some means were found to automate the platen press unit so as to increase its output capacity and avoid the necessity of using workers to load and unload the press unit, without sacrificing its maximum efficiency output of high quality juice.